The present invention relates to a hydrogen manufacturing apparatus and a method thereof for manufacturing hydrogen, while suppressing permeation of tritium.
Recently, hydrogen is manufactured by using fossil resources as energy sources or fossil resources as raw material. This is contradictory to the idea of introducing hydrogen energy in order to utilize energy that is friendly to the environment because of not discharging carbon dioxide and so on. To dissolve this contradiction, it is necessary to manufacture hydrogen by using only natural energy and atomic power as energy sources and water as raw material.
As a method to do so, manufacturing hydrogen by utilizing atomic energy is attracting attention. Research and development efforts has been paid for manufacturing hydrogen by means of high temperature gas reactor as the most promising manufacturing method (see, for example, Japanese Patent Publication Numbers Hei 5-213602 (A), 2005-170707 (A) and 2005-289740 (A), (the entire contents of which are incorporated herein by reference)).
Heat discharged from a high temperature gas reactor is subjected to heat exchange with secondary helium gas by way of an intermediate heat exchanger. Heat collected by the intermediate heat exchanger is used as heat source for steam reforming reactions of methane, steam manufacturing and so on.
On the other hand, steam reforming reactions are conducted in steam reformers. A plurality of reaction tubes are suspended in the inside of a steam reformer. Secondary helium gas is made to flow outside the reaction tubes. Process gas, or the raw material gas and the generated gas flow inside the reaction tubes. As the process gas in the inside of the reaction tubes are heated by secondary helium gas flowing outside the reaction tubes, it is thermo-chemically decomposed to produce hydrogen.
The above-described reaction technique can be applied to reactors for the Iodine-Sulfur (IS) process that is another hydrogen manufacturing method. With the IS process, water is thermo-chemically decomposed to produce hydrogen as iodine and sulfuric acid are made to internally circulate.
As described above, heat produced from a nuclear plant is utilized to manufacture hydrogen. Tritium that is an isotopic element of hydrogen is produced when manufacturing hydrogen. Tritium is an radioactive element and can adversely affect human bodies so that it is necessary to confine tritium within the plant as much as possible without discharging tritium to the outside of the plant.
However, tritium has a property of permeating solid walls. Tritium can pass through the heat conductor tubes of intermediate heat exchangers and the catalyst tubes of steam reformers to become mixed with manufactured hydrogen.
These apparatus are required to be strong, manufacturable and anti-corrodible and hence it is desirable that they are made of metal.
However, since tritium can permeate metal, measures have to be taken to suppress permeation of tritium.
In view of the above-identified problems, it is therefore the object of the present invention to provide a hydrogen magnification apparatus and a method thereof that can manufacture hydrogen, suppressing permeation of tritium through metal-made internal structures such as piping that tritium can permeate.